1. Field of the Invention
This invention relates in general to gas discharge devices disclosed in my co-pending U.S. application Ser. No. 424,692, filed Dec. 14, 1973, now U.S. Pat. No. 3,885,195 and more particular to a novel gas discharge flat panel display apparatus which comprises a plurality of gas discharge cells where phosphor materials emitting predetermined color lights are deposited at the predetermined position.
2. Description of the Prior Art
In the prior art, a color phosphor discharge tube is formed as shown in FIGS. 1 to 3. In this prior art example, a tube is formed of back and top plates 2 and 3 which are made of an insulating material such, for example, as glass. In this case, at least one of the plates 2 and 3, for example, the top plate 3 is made transparent or semi-transparent. The back and top plates 2 and 3 are arranged in opposed relation and sealed with, for example, frit glass 4 along their marginal edges to form a flat space 5 between them.
A first electrode group Y, which consists of a plurality of electrodes y.sub.1, y.sub.2, y.sub.3, . . . each having a predetermined width and arranged parallel with one another at a predetermined pitch in one direction, for example, row direction, is formed on the inner surface of the back plate 2. For example, the first electrode group Y is formed in such a manner that a resistive paint such as RuO.sub.2 is coated on the back plate 2 with a predetermined pattern by printing and then plated with nickel thereon. Respective one ends of the parallel electrodes y.sub.1, y.sub.2, y.sub.3, . . . are extended beyond one edge of the back plate 2 to the outside of the space 5 to form terminal portions 6, respectively.
An insulator group G, which consists of a plurality of band insulating ribs g.sub.1, g.sub.2, g.sub.3, . . . , each having a predetermined width and arranged parallel with one another at a predetermined pitch in column direction or to intersect each of the parallel electrodes y.sub.1, y.sub.2, y.sub.3, . . . at substantially right angles, is formed on the inner surface of the back plate 2. This insulator group G is made by, for example, printing glass with a predetermined pattern on the inner surface of the back plate 2 or coating glass all over the inner surface of the back plate 2 and etching away unnecessary portions thereof to be the predetermined pattern. The thickness or height of each of the parallel insulating ribs g.sub.1, g.sub.2, g.sub.3, . . is selected in response to the distance between the back and top plates 2 and 3 to be desired.
A barrier electrode group S, which consists of a plurality of barrier electrodes s.sub.1, s.sub.2, s.sub.3, . . . , is formed on the inner surface of the top plate 3 such that they are arranged at the positions corresponding to the parallel insulating ribs g.sub.1,g.sub.2, g.sub.3, . . . , respectively, and extend in the extending directions of the latter. Further, a second electrode group X, which consists of a plurality of electrodes x.sub.1, x.sub.2, x.sub.3, . . . to be transparent anode electrodes, is formed on the inner surface of the top plate 3 such that the electrodes x.sub.1, x.sub.2,x.sub.3, . . . are located between adjacent ones of the parallel barrier electrodes s.sub.1, s.sub.2, s.sub.3, . . . and parallel to the latter, respectively.
The respective parallel electrodes s.sub.1, s.sub.2, s.sub.3, . . . and x.sub.1, x.sub.2, x.sub.3, . . . of the barrier electrode group S and second electrode group X may be formed of the same material such as, for example, Nesa (trade name) which is transparent conductive material at the same time.
Respective one ends of the barrier electrodes s.sub.1, s.sub.2, s.sub.3, . . . are extended to one side edge of the top plate 3 to form a common terminal 7 which is located outside the space 5.
One ends of the respective parallel electrodes x.sub.1, x.sub.2, x.sub.3, . . . of the second electrode group X are extended to the other side edge of the top plate 3 outside the space 5 to form terminal portions 8, respectively.
Thus, discharge cells are formed at the respective intersections of the parallel electrodes y.sub.1, y.sub.2, y.sub.3, . . . of the first electrode group Y and those x.sub.1, x.sub.2, x.sub.3, . . . of the second electrode group X.
Phosphors P.sub.R, P.sub.G and P.sub.B, which may emit predetermined color lights such as, for example, red, green and blue color lights, are provided in the discharge cells, respectively. By way of example, the red phosphor P.sub.R is printed or deposited on the inner surface of the top plate 3 at the both sides of every fourth electrode or x.sub.1, x.sub.4, x.sub.7, . . . of the second electrode group X along thereof; the green phosphor P.sub.G is printed or deposited on the inner surface of the top plate 3 at the both sides of the electrodes x.sub.2, x.sub.5, x.sub.8, . . . along thereof; and the blue phosphor P.sub.B is printed or deposited on the inner surface of the top plate 3 at the both sides of the electrodes x.sub.3, x.sub.6, x.sub.9, . . . along thereof, respectively.
The back and top plates 2 and 3 are opposed in such a manner that the parallel insulating ribs g.sub.1, g.sub.2, g.sub.3, . . . formed on the inner surface of the back plate 2 are contacted with the corresponding parallel barrier electrodes s.sub.1, s.sub.2, s.sub.3, . . . formed on the inner surface of the top plate 3 to determine the distance between the opposed surfaces of the back and top plates 2 and 3 by the height of the insulating ribs g.sub.1, g.sub.2, g.sub.3, . . . substantially, and then the corresponding marginal edges of both the plates 2 and 3 are sealed up by the frit glass 4 as described above to form the space 5.
Thus, the space 5 formed in the tube 1 is divided by the insulating ribs g.sub.1, g.sub.2, g.sub.3, . . . into a plurality of band spaces a.sub.1, a.sub.2, a.sub.3, . . . which include therein the electrodes x.sub.1, x.sub.2, x.sub.3, . . . of the second electrode group X, respectively. In this case, the insulating ribs g.sub.1, g.sub.2, g.sub.3, . . . are so formed that the band spaces a.sub.1, a.sub.2, a.sub.3, . . . are communicated with one another at their one ends or non-effective portions as shown in FIG. 1.
Then, the envelop 1 or the space 5 thereof is evacuated and filled with a rare-gas at a predetermined low pressure.
The respective electrodes y.sub.1, y.sub.2, y.sub.3, . . . of the first electrode group Y are sequentially supplied with an off voltage of, for example, 100 V to an on voltage of 0 V in time division manner by a driving circuit 10, while the respective electrodes x.sub.1, x.sub.2, x.sub.3, . . . of the second electrode group X are supplied with voltages from 200 to 250 V by a driving circuit 11 sequentially or instantaneously in response to the display signal. Thus, discharges are caused at the intersections of the electrodes x.sub.1, x.sub.2, x.sub.3, . . . and the electrodes y.sub.1, y.sub.2, y.sub.3, . . . to which the on voltages are supplied or at the discharge cells to excite the phosphors P.sub.R, P.sub.G and P.sub.B in the discharge cells which then emit red, green and blue color lights, respectively. In this case, the luminances of the lights emitted from the phosphors respond to the voltage differences between the electrodes x.sub.1, x.sub.2, x.sub.3, . . . and those y.sub.1, y.sub.2, y.sub.3, . . . which correspond to the display signals to produce a color picture by combining the color lights emitted from the respective phosphors which are excited in a dot-or line-sequence manner. The produced picture can be viewed through, for example, the top plate 3.
The respective barrier electrodes s.sub.1, s.sub.2, s.sub.3, . . . of the barrier electrode group S are supplied from a DC voltage source 12 with a constant DC voltage which is about a half of the discharge voltage, for example, a voltage of 90 to 100 V so that the glows, which otherwise may expand along the cathodes or the electrodes y.sub.1, y.sub.2, y.sub.3, . . . of the first electrode group Y which are supplied with the on voltages, are prevented from being expanded by the insulating ribs g.sub.1, g.sub.2, g.sub.3, . . . , and also the ions and electrons produced by the glows are repelled and annihilated by the barrier electrodes s.sub.1, s.sub.2, s.sub.3, . . . to be lost in electric charges at the ribs or on the inner surface of the plates in the vicinity thereof. Thus, the expansion thereof is prevented to avoid any cross-talk.
In the prior art color discharge tube as described above, the respective color phosphors P.sub.R, P.sub.G and P.sub.B are located in the discharge cells arranged in matrix or near the intersections of the electrodes y.sub.1, y.sub.2, y.sub.3, . . . , and those x.sub.1, x.sub.2, x.sub.3, . . . of the first and second electrode groups Y and X. In the above prior art example, the phosphors P.sub.R, P.sub.G and P.sub.B are coated on the inner surface of the top plate 3 which is common to the respective discharge cells. In order to coat all the phosphors P.sub.R, P.sub.G and P.sub.B on the common component or top plate 3 with the predetermined pattern, such a method is employed that they are optically printed by using, for example, a photo-binder. By way of example, a slurry consisting of a first color phosphor or red phosphor and the photo-binder is coated on all the inner surface of the top plate 3 on which the electrode group X is formed, their predetermined portions are optically printed and then unnecessary portions thereof are removed by the development. Another slurry consisting of a second phosphor or green phosphor and the photo-binder is coated on the inner surface of the top plate 3 including the coated red phosphor, then subjected to the photo-printing process and to the developing process to form the green phosphor. A slurry consisting of a third phosphor or blue phosphor and the photo-binder is coated on the inner surface of the top plate 3 and then subjected to the similar processed to form the blue phosphor.
With such a coating method, since the green and blue phosphor slurries are coated on the first or red phosphor, there is a fear that the first phosphor is blurred or contaminated and color blur occurs.
In the case where the color phosphors are formed by using a photo-resist or mask layer, printing method, etching method or the like, since a resist, mask or printing screen for coating two different phosphors contacts with or is coated on the firstly formed phosphor, this phosphor may be contaminated especially.
In general, such a method that three kinds of phosphors are coated on the same plate results in the arranging pitches thereof being small, so that such a coating is difficult by any technique.